New national standard for power batteries to be issued, 5-minute warning becomes standard

Since the Tesla spontaneous combustion incident this year , many new energy vehicle companies have become popular one after another as if they were under a curse. However, this "fire" has extinguished the market's enthusiasm for new energy vehicles and also caused serious doubts about new energy vehicles.

How to regulate safety issues in the new energy vehicle industry and how to better protect the safety of consumers are answers that the industry urgently needs to give.

The new national standard is about to be released, and the test content becomes a mandatory requirement

Recently, First Electric obtained the draft of GB "Safety Requirements for Power Batteries for Electric Vehicles " from a source and learned that the new national standard has entered the WTO review stage and will be officially released soon. This new national standard, which combines and expands GB/T 31485-2015 "Safety Requirements and Test Methods for Power Batteries for Electric Vehicles" and GB/T 31467.3-2015 "Lithium-ion Power Battery Packs and Systems for Electric Vehicles Part 3: Safety Requirements and Test Methods", was released for comments at the beginning of last year. The upgrade from "GB/T" to "GB" means that after the official implementation, all tests in the new national standard will become mandatory requirements, including the electric vehicle escape time that consumers are most concerned about.

According to the draft of the Safety Requirements for Power Batteries for Electric Vehicles, there are 22 mandatory test items for power batteries, including battery cell tests (6 items) and battery pack or system tests (16 items).

The new national standard has six test requirements for battery cells: over-discharge, over-charge, external short circuit, heating, temperature cycle and extrusion, which is 4 fewer than GB/T31485-2015. The battery pack test has two fewer tests: drop and flip, while all module-level tests have been cancelled.

(GB/T31485-2015 Single battery test procedure)

Battery cell puncture test cancelled, water immersion test more difficult

Among the individual test items, the puncture test, which is considered the most stringent, has been cancelled in the new national standard, which is consistent with the draft for comments released at the beginning of last year.

However, from the relevant documents, it can be seen that Annex 3 of the "Regulations on the Access Management of New Energy Vehicle Production Enterprises and Products" (hereinafter referred to as the "Access Management Regulations"), which came into effect on July 1, 2017, mentioned that the acupuncture test will not be implemented for the time being.

In the draft for comments released on January 25 last year, the reasons for canceling the puncture test were explained again. In addition to the fact that the puncture test is not temporarily implemented in the Access Management Regulations, the drafting team found that the puncture test was not used in the IEC and other standards and believed that the puncture test was inconsistent with the actual failure mode. These are the other two reasons for canceling the puncture test in the new national standard.

Regarding the cancellation of the needle puncture test, some industry insiders believe that needle puncture is an insurmountable hurdle for most manufacturers, especially for ternary batteries. Therefore, many suppliers are secretly glad that the needle puncture requirement has been cancelled. However, the industry's safety risks are increasing.

In this regard, Guo Dong, deputy leader of the expert committee of the new energy vehicle safety education project of the Ministry of Emergency Management, told First Electric that the probability of acupuncture scenarios occurring in the use scenarios of new energy vehicles is extremely low, but this test is necessary for batteries for consumer electronics and power tools.

Although the new national standard has cancelled the needle penetration test for battery cells, it is interesting that in the new national standard Appendix C on the analysis and verification report on thermal diffusion occupant protection, the needle penetration trigger appears in the optional method recommended as a thermal diffusion test. At the same time, the description of "not yet implemented" in the "Access Management Regulations" is also rather ambiguous, which leaves room for speculation as to whether the needle penetration test will be resumed in the future.

Another important change in the revision of the new national standard is to change the seawater immersion test to a water immersion safety test. First, the test object is changed from a battery pack or system to a battery pack or system that has passed the 8.2.1 vibration test. Secondly, in addition to the seawater immersion in the old national standard, a new test method is added: the test object is tested with reference to the method and process described in 14.2.7 of GB/T 4208-2017. After the test according to method 2, it is necessary to meet the IPX waterproof level 7 standard, which is slightly different from the draft for comments. Some industry insiders believe that this is one of the difficulties in the test in the new national standard.

In this regard, a relevant technician from a leading battery company told First Electric that the difficulty of this test has not increased significantly, but it has put forward higher requirements on the design and manufacturing of battery packs or systems, and it is necessary to consider the safety of water immersion after use of the battery pack or system.

5-minute safety warning will become standard

Among the changes in the new national standard, the most noteworthy one is the newly added thermal diffusion test.

In April this year, a Tesla caught fire in a parking garage under a residential community in Shanghai. In just a few seconds, the car body was engulfed in flames, and the vehicles parked nearby were also not spared. The shocking scene caused consumers to have huge doubts about the safety of new energy vehicles and brought panic.

On June 17, the Ministry of Industry and Information Technology issued the "Notice on Carrying out Safety Hazard Inspection of New Energy Vehicles", urging all new energy vehicle manufacturers to carry out safety hazard inspection of new energy vehicles produced by the company. In order to strengthen in-process and post-event supervision, the mandatory thermal diffusion test is imperative. The new national standard to be issued this time has included it in the mandatory implementation items. First Electric believes that this is a great progress, especially its test requirements mention that "the battery pack or system should provide a thermal event alarm signal 5 minutes before the passenger compartment is in danger due to thermal runaway of a single battery causing thermal diffusion (serving the thermal event alarm of the whole vehicle to remind passengers to evacuate)", which is indeed an extra layer of protection for consumers. This means that after the implementation of the new national standard, new energy vehicles "born" will have a 5-minute warning as standard.

But it is undeniable that the test is not easy to pass, especially for ternary material batteries. A friend of mine who is engaged in battery testing used four words to describe the test results when talking about the thermal diffusion test of ternary batteries for a battery company a few days ago - quite exciting. As for whether it is praise or criticism, there is no need to say more. Therefore, some people believe that after the official implementation of the new national standard, lithium iron phosphate batteries are likely to make a comeback and occupy the market share of ternary batteries. But some industry insiders have different views.

The director of industry research at a well-known investment institution told First Electric: "If nothing unexpected happens, the products of the drafting units of the new national standard should all meet this requirement. It can be said that this is a relatively basic requirement, and the new national standard only regulates it. Unlike the previous new national standard for two-wheeled electric vehicles , some existing lead-acid battery products are directly excluded, which has a greater impact on the industry. I think the role of the new national standard should be just a normative document. From the perspective of heat diffusion, some new companies and leading companies should be able to pass, but it may be a bit difficult for some old companies without such strong technical conditions."

Guo Dong also has a similar view. He believes that the introduction of the new national standard is more meaningful in making the future accident identification process of new energy vehicles more traceable, rather than guiding the design of corporate products. The standard is only the bottom line that product safety needs to meet, rather than a high standard. The solution to safety issues depends on the quality and awareness of the people, the management of the government and the self-discipline of enterprises. Our country is not yet a first-class safety country. Individual measures cannot fundamentally solve the problem. Even if the test sample passes, how to ensure the consistency of subsequent products is still a big issue for enterprises.

In conclusion:

When comparing the old and new versions of the national standard, I found something interesting: CATL stood out from the other drafting units in the new national standard and became the responsible drafting unit alongside China Automotive Research Institute. In just a few years, CATL has become the "leader" in the industry.

(GB/T 31485-2015)

(Draft for approval of new national standard)

Recently, when the author communicated with CATL, they said that they did not care much about the threat atmosphere created by the outside world against Japanese and Korean companies. CATL has always been moving forward at its own pace and of course will not take it lightly and is not afraid of direct competition.